Hoisting crane and offshore vessel

ABSTRACT

The present invention relates to a hoisting crane comprising a substantially hollow vertical column, a jib and topping means for pivoting the jib up and down, comprising a jib winch and a jib hoisting cable. The crane further comprises hoisting means for hoisting a load, comprising a hoisting winch and an associated hoisting cable, the hoisting winch being disposed in the column, so that the hoisting cable extends from the winch through the hollow vertical column. The jib winch and the hoisting winch are arranged on a rotatable winch support, which is rotatable about a rotation axis substantially parallel with the vertical column, such that the winch support is mounted movable with respect to the vertical column. The hoisting crane further comprises a deep water winch positioned below the movable winch support and an associated deep water cable for raising and lowering a load extending through the rotation axis of the movable winch support, so that the deep water cable extends from the deep water winch through the hollow vertical column. The present invention further relates to a vessel provided with such a crane.

The invention relates to a hoisting crane in accordance with thepreamble of claim 1. Such a hoisting crane has previously been describedby the applicant in PCT/NL2005/000443.

A disadvantage of such known hoisting cranes is that the range of loadsthat can be hoisted at a desired hoisting rate is limited. The winch andhoisting cable of the hoisting crane determine its capacity. With reevedhoisting cables heavier loads can be hoisted, but at a lower rate. Inorder to hoist heavier loads at the same rate, the required weight anddimension of the hoisting cable and winch increase rapidly. This is thereason why for known hoisting cranes a compromise of hoisting cable,winch and capacity of the crane has to be chosen.

It is an object of the invention to propose an improved hoisting crane.To this end, the invention provides a hoisting crane in accordance withthe preamble of claim 1, which is characterised in that the hoistingcrane further comprises a deep water winch positioned below the movablewinch support and an associated deep water cable for hoisting a loadextending through the center of the movable winch support, so that thedeep water cable extends from the deep water winch through the hollowvertical column to the top cable guide and then to a hoisting cableguide on the jib.

An advantage of such a crane is that the range of loads that can behoisted at a desired hoisting rate is increased due to the applicabilityof the combination of hoisting means and a deepwater lowering system.The conventional hoisting system allows hoisting of loads withincreasing weight at decreasing hoisting rate, and the deepwaterlowering system specifically allows hoisting of relatively large weightloads over large distances (in deep water) with a reasonable hoistingrate. A deepwater lowering system according to the invention typicallycomprises a high-capacity winch and a cable having a relatively largediameter, in a preferred embodiment a cable having a diameter of up to109 mm and a length of up to 4000 meters.

In a preferred embodiment, the deep water winch is mounted in a fixedorientation with respect to the vertical column. Because the deep watercable for hoisting a load extends through the center of the movablewinch support, the deep water system is operable at any orientation ofthe jib.

In an alternative embodiment, the deep water winch is arranged on amovable deep water winch support, which is mounted moveable with respectto the vertical column. This embodiment is less preferred since thelarge mass of the deep water winch limits its movability considerably.

Further advantageous embodiments are described in the dependent claimsand in the following description with reference to the drawing.

In the drawing:

FIG. 1 diagrammatically depicts an offshore vessel which is suitable,inter alia, for laying a pipeline on the seabed,

FIG. 2 shows the hoisting crane at the rear side of the vessel shown inFIG. 1, partially in the form of a cut-away view,

FIG. 3 shows the hoisting crane from FIG. 2 from a different direction,

FIG. 4 shows a view of the hoisting crane shown in FIGS. 2 and 3 fromabove.

FIG. 1 shows an offshore vessel 1 which is suitable, inter alia, forlaying a pipeline on the seabed. Obviously the vessel could also be of adifferent type, e.g. a semi-submersible. The vessel could also be aplatform, such as a tension leg platform or otherwise.

The vessel 1 has a hull 2 with a working deck 3 and, at the front of thehull 2, a superstructure 4 for crew accommodation, etc.

The vessel 1 is provided with a pipeline-laying installation of theS-lay type, with one or more welding stations on the working deck 3, forcoupling pipeline sections 9 a in a substantially horizontalorientation. On the working deck 3 there are also what are known astensioners 8 for carrying the weight of the pipeline 9 which is hangingdownwards from the vessel 1.

Furthermore, the vessel 1 has a stinger 5 which projects outside thehull 2 of the vessel 1 at the rear side of the vessel 1, engages on thehull 2 at an engagement point such that it can pivot about asubstantially horizontal pivot structure 6 and forms a downwardly curvedsupport for pipeline moving towards the seabed.

Furthermore, the vessel 1 has a hoisting crane 20 according to theinvention, in this embodiment disposed in the vicinity of the same sideof the hull as the stinger 5, which hoisting crane 20 has a verticalstructure fixed to the hull 2. The hoisting crane 20 will be describedin more detail below. Here, the crane 20 is disposed above the locationwhere the pipeline 9 leaves the working deck 3, on the longitudinal axisof the vessel 1.

The hoisting crane 20, which is illustrated in detail in FIGS. 2-4, hasa substantially hollow vertical column 21 with a foot 22, which in thiscase is fixed to the hull 2 of the vessel 1. Furthermore, the column 21has a top 23.

The hoisting crane 20 has a jib 24, which is illustrated in twodifferent positions in FIG. 1. An annular bearing structure 25 extendsaround the vertical column 21 and guides and carries a jib connectionmember 26, so that the jib connection member 26, and therefore the jib24, can rotate about the column 21.

In this case, the jib connection member 26 forms a substantiallyhorizontal pivot axis, so that the jib 24 can also be pivoted up anddown. There is at least one drive motor 27 for displacing the jibconnection member 26 along the annular bearing structure 25. By way ofexample, the annular bearing structure 25 comprises one or more guidetracks which extend around the column 21 and on which an annularcomponent 28 of the jib connection member 26 is supported via runningwheels. Jib securing supports 29 are arranged on the component 28 at twopositions. The drive motor 27 may, for example, drive a pinion whichengages with a toothed track around the column 21.

To pivot the jib 24 up and down, there is a topping winch 30 providedwith a topping cable 31 which engages on the jib 24.

Furthermore, the hoisting crane 20 comprises a hoisting winch 35 forraising and lowering a load, with an associated hoisting cable 36 and ahoisting hook 37.

According to the invention, the hoisting crane 20 comprises a deep waterwinch 82 and an associated deep water cable 81 for raising and loweringa load. In the shown embodiment the deep water cable 81 is guided via alower cable pulley assembly 83. Preferably, such deep water winch andcable allow the lowering of subsea structures to water depths of atleast 1000 meters, more preferably up to 3000 meters.

Such deep water winch and deep water cable may preferably be embodied asan abandonment and recovery (A&R) winch and cable. Such A&R winch andcable is used in pipe lay operations to be able to abandon and recover apreviously launched pipeline. For such purposes, it is required that theentire weight of the previously launched pipeline is suspended from anA&R wire.

At the top 23 of the column 21 there is a top cable guide 40 providedwith a cable pulley assembly 41 for the topping cable 31, and with acable pulley assembly 42 for the hoisting cable 36, and with a cablepulley assembly 80 for the deep water cable 81.

One or more cable pulley assemblies 43 for the hoisting cable 36 and/orthe deep water cable 36 and a cable pulley assembly 44 for the toppingcable 31 are arranged on the jib 24. The number of cable parts for eachcable can be selected as appropriate by the person skilled in the art.

The winches 30 and 35 are in this case disposed in the foot 22 of thevertical column 21, so that the topping cable 31 and the hoisting cable36 extend from the associated winch 30, 35 upward, through the hollowvertical column 21 to the top cable guide 40 and then towards the cableguides 43, 44 on the jib 24.

The top cable guide 40 has a rotary bearing structure, for example withone or more running tracks around the top of the column 21 and runningwheels, engaging on the running tracks, of a structural part on whichthe cable pulley assemblies are mounted. As a result, the top cableguide 40 can follow rotary movements of the jib about the verticalcolumn 21 and adopt substantially the same angular position as the jib24.

The top cable guide 40 may have an associated drive motor assembly whichensures that the top cable guide 40 follows the rotary movements of thejib 24 about the column 21, but an embodiment without drive motorassembly is preferred.

The jib winch 31 and the hoisting winch 35 are arranged on a rotatablewinch support 50, which is rotatable about a rotation axis substantiallyparallel with the vertical column 21. The movable winch support 50,which is mounted movably with respect to the vertical column 21. Thewinch support 50 here is located in the vertical crane structure,preferably in the region of the foot 22 under the circular cross sectionpart of the column 21, and is mechanically decoupled from the top cableguide 40. The support 50 could e.g. also be arranged in the hull of thevessel below the column, e.g. the foot could have an extension whichextends into the hull.

In the example shown, the winch support 50 is a substantially circularplatform which at its circumference is mounted in an annular bearing 51,with the winches 31, 35 arranged on the platform. The annular bearing 51is in this case such that the platform can rotate about a vertical axiswhich coincides with the axis of rotation of the top cable guide. Thebearing can have any appropriate design including trolleys running alonga circular track.

The rotatable winch support 50 has an associated drive motor assembly 52for moving the winch support 50, in such a manner that the winch support50 maintains a substantially constant orientation with respect to thejib 24 in the event of rotary movements of the jib 24 about the verticalcolumn 21. The orientation of the winch support 50 with respect to thetop table guide 40 likewise remains substantially constant, since itsmovements are once again the consequence of rotary movements of the jib24.

According to the present invention, the deep water winch 82 ispositioned below the movable winch support 50.

The deep water winch 82 may be embodied as a linear winch, or a tractionwinch, or any other suitable type of winch.

Preferably, the deep water winch 82 and associated or integrated storagedrum for the deep water cable is positioned in the hold of the vessel.Preferably, the deep water winch and associated or integrated storagedrum is positioned as low as possible due to its large weight. The deepwater winch 82 and the cable pulley assembly 83 are mounted on a deepwater winch support 84, which is preferably mounted in a fixedorientation with respect to the vertical column 21,22.

Alternatively, the deep water winch support is mounted moveable withrespect to the vertical column 21, 22. In a possible embodiment, it isenvisaged to connect the movable deep water winch support 84 to themovable winch support 50 of the jib winch and the hoisting winch 31, 35,such that the supports 84,50 are movable synchronously.

The associated deep water cable 81 extends from the deep water winch 82through the rotation axis of the movable winch support, which is in thiscase through the center of the movable winch support 50, to the topcable guide and then to a hoisting cable guide on the jib.

In the embodiment shown, there is an angle sensor 60 for detecting theposition of the component 28 of the jib connection member 26 withrespect to the vertical column 21, the drive motor assembly 52 of thewinch support 50 having associated control means 53 which are inoperative contact with the angle sensor 60.

The winches 31, 35 each have an associated electrical (orelectro-hydraulic) winch drive motor assembly 38, 39 which is disposedon the movable winch support 50. The electrical energy required issupplied by generators disposed elsewhere on the vessel, at a distancefrom the movable winch support 50. One or more sliding contacts (notshown) are provided in the electrical connection between thesegenerators and the winch drive motor assemblies 38, 39.

In a variant which is not shown, the winch support 50 can rotate about avertical shaft, this shaft being provided with one or more slidingcontacts. In such an embodiment, the deep water cable extends trough thecentre of such shaft.

Via the one or more sliding contacts, a power current supply ispreferably fed to the electrical equipment on the winch support 50.

The hoisting crane 20 is provided with a cab 70 for a hoisting craneoperator, which cab 70 is in this case carried by the annular bearingstructure 25 to which the jib 24 is secured, so that the cab 70 canrotate with the jib about the vertical column 21.

In the cab 70 there are at least control members (not shown) foroperating the winch 35 of the hoisting cable 36 and for operating thewinch 31 of the topping cable 31. The winch drive motor assemblies 38,39 have associated control means (not shown) which are in wirelesscommunication with the associated control members in the cab 70. By wayof example, a plurality of wireless transmission/reception units aredisposed around the vertical column, in or in the vicinity of the pathof the cab 70 around the vertical column.

The control means, for example electronic control equipment, for the oneor more winches on the winch support 50 are preferably also positionedon this winch support 50.

It can be seen from the figures that, as is preferred, the verticalcolumn 21 has a substantially continuous outer wall. In this case, thehorizontal section through the vertical column is substantially circularfrom the jib connection member to the top 23, with the cross sectiongradually decreasing towards the top of the column. The foot 22 of thecolumn 21 is substantially rectangular, which has the advantage that thefoot 22 can easily be secured (by welding or using bolts) to thelongitudinal and cross bulkheads of the hull 2 of the vessel 1. In avariant which is not shown, the vertical column is partly or completelya framework of bars.

It can be seen from FIG. 1 that a load-bearing connecting structure 80,which holds the stinger in a desired position, extends between thevertical structure of the hoisting crane 20 at a location above thepoint of engagement 6 of the stinger 5 on the vessel hull 2 (in thiscase in the vicinity of the annular bearing structure for the jib 24),and the stinger 5, at a location remote from the point of engagement 6of the stinger 5 on the vessel hull 2.

Using the vertical structure, here the foot 22, of the hoisting crane 20as a point of engagement for the structure 80 makes it possible todispense with additional structural components for holding the stingerin place, such as cantilevers projecting outside the hull 2.

The vessel 1 can be used to lay a pipeline 9, but also for hoistingwork, such as the hoisting work carried out, for example, in theoffshore industry when installing platforms, underwater installations,etc.

1. Hoisting crane comprising: a substantially hollow vertical columnwith a foot which is or can be fixed to a support, and with a top, ajib, an annular bearing structure, which extends around the verticalcolumn and guides and carries a jib connection member, so that the jibconnection member can rotate about the column, the jib connection memberforming a substantially horizontal pivot axis so that the jib can bepivoted up and down, topping means for pivoting the jib up and down,comprising a jib winch and a jib hoisting cable, a top cable guide atthe top of the vertical column; the top cable guide comprising a rotarybearing structure, so that the top cable guide can follow rotarymovements of the jib about the vertical column and adopts substantiallythe same angular position as the jib, one or more hoisting cable guideson the jib of the hoisting crane; hoisting means for hoisting a load,comprising a hoisting winch and an associated hoisting cable; thehoisting winch being disposed in the column, preferably in the vicinityof the foot of the vertical column, so that the hoisting cable extendsfrom the winch through the hollow vertical column to the top cable guideand then to a hoisting cable guide on the jib, wherein the jib winch andthe hoisting winch are arranged on a rotatable winch support, which isrotatable about a rotation axis substantially parallel with the verticalcolumn, such that the winch support is mounted movable with respect tothe vertical column; the winch support having an associated drive motorassembly for moving the winch support, in such a manner that the winchsupport maintains a substantially constant orientation with respect tothe jib in the event of rotary movements of the jib about the verticalcolumn, wherein the hoisting crane further comprises a deep water winchpositioned below the movable winch support and an associated deep watercable for raising and lowering a load extending through the rotationaxis of the movable winch support, so that the deep water cable extendsfrom the deep water winch through the hollow vertical column to the topcable guide and then to a hoisting cable guide on the jib.
 2. Hoistingcrane according to claim 1, wherein the deep water winch is mounted in afixed orientation with respect to the vertical column.
 3. Hoisting craneaccording to claim 1, in which the vertical column has a substantiallycontinuous outer wall.
 4. Hoisting crane according to claim 3, in whichthe horizontal section through the vertical column is substantiallycircular, and in which the cross section preferably decreases graduallytowards the top of the column.
 5. Hoisting crane according to claim 1,in which the foot of the column is substantially rectangular. 6.Hoisting crane according to claim 1, in which the vertical column is atleast in part a framework of bars.
 7. Hoisting crane according to claim1, wherein the deep water winch is arranged on a movable deep waterwinch support, which is mounted moveable with respect to the verticalcolumn.
 8. Hoisting crane according to claim 7, wherein the movable deepwater winch support is connected to the movable winch support of the jibwinch and the hoisting winch such that the supports are movablesynchronously.
 9. Vessel provided with a hoisting crane according toclaim
 1. 10. Offshore vessel, suitable, inter alia, for laying apipeline on the seabed, comprising a hoisting crane according to claim1, which hoisting crane has a vertical structure fixed to the hull. 11.Hoisting crane according to claim 2, in which the vertical column has asubstantially continuous outer wall.
 12. Hoisting crane according toclaim 11, in which the horizontal section through the vertical column issubstantially circular, and in which the cross section preferablydecreases gradually towards the top of the column.
 13. Hoisting craneaccording to claim 2, in which the foot of the column is substantiallyrectangular.
 14. Hoisting crane according to claim 3, in which the footof the column is substantially rectangular.
 15. Hoisting crane accordingto claim 4, in which the foot of the column is substantiallyrectangular.
 16. Hoisting crane according to claim 2, in which thevertical column is at least in part a framework of bars.
 17. Hoistingcrane according to claim 3, in which the vertical column is at least inpart a framework of bars.
 18. Hoisting crane according to claim 4, inwhich the vertical column is at least in part a framework of bars. 19.Hoisting crane according to claim 5, in which the vertical column is atleast in part a framework of bars.